Inhibition and promotion of copper corrosion by CTAB in a microreactor system

The Role of Some Cationic Surfactants Based on Thiazine as Corrosion Inhibitors in Petroleum Applications: Experimental and Theoretical Approach

Two cationic surfactants based on thiazine, dodecyl thiazin bromide (DTB) and hexyl thiazin bromide (HTB), were synthesized, characterized, and investigated as corrosion inhibitors for API X-65 type steel in oil wells' formation water under an H₂S environment. Various spectroscopic techniques such as FTIR and ¹H NMR were used to confirm the DTB and HTB chemical structures. The corrosion inhibition efficiency of the selected compounds was investigated using both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The innovation of the current study is the existence of a long chain in the inhibitor molecule, which leads to an increase in the performance of the surfactant as a corrosion inhibitor, due to the increase in the surface area per molecule. It was found that these surfactants act as mixed-type inhibitors, leading to suppression of both the cathodic and the anodic processes by its adsorption on the electrode surface according to the Langmuir adsorption isotherm. Carbon steel's inhibitory mechanism was studied using an analogous circuit. The scanning electron microscope technique was used as a suitable analysis tool to show the nature of the layer designed on carbon steel. Quantum chemical calculations and Monte Carlo simulation techniques were used to support the obtained experimental results. Finally, a suitable mechanism for the inhibition process was proposed and discussed.

Corrosion Control of Carbon Steel in Water-Based Mud by Nanosized Metallo-Cationic Surfactant Complexes During Drilling Operations

In this work, three nanometal complexes named cetyltrimethyammonium dibromodichloro zincate (CT-Zn), cetyltrimethyammonium dibromodichloro cuprate (CT-Cu), and cetyltrimethyammonium dibromodichloro manganesate (CT-Mn) were prepared, characterized, and evaluated as corrosion inhibitors for carbon steel in water-based mud (WBM). The chemical structure of the prepared complexes was confirmed by the use of Fourier transform infrared spectroscopy, Raman spectroscopy, elemental analysis, atomic absorption spectroscopy, dynamic light scattering, and thermogravimetric analysis techniques. The surface tension of the complexes was measured. The critical micelle concentrations and some of the surface properties were also determined. The compounds were evaluated as corrosion inhibitors for carbon steel in the prepared WBM using potentiodynamic polarization and weight loss methods during the static and dynamic conditions of the drilling operations. The results indicated that the prepared metal complexes showed high anticorrosion action as the inhibition efficiency increased gradually with the increase in the concentrations of the prepared complexes until it reached the maximum value (93.1%) at 300 ppm for CT-Cu. The order of inhibition efficiency of these inhibitors was as follows: CT-Cu > CT-Zn > CT-Mn. The polarization curves showed that these complexes acted as mixed-type inhibitors. According to the results, the adsorption of these compounds obeyed Langmuir adsorption isotherm. Surface analysis of the carbon steel samples was investigated using scanning electron microscopy, energy dispersive X-ray, and X-ray diffraction techniques. Rheological properties, gel strength, thixotropy, and filtration properties were also measured according to American Petroleum Institute specifications.

Corrosion inhibition of iron surfaces with phosphatidic acid

Preventing the corrosion of iron in inaccessible structures requires a coating method that reaches all surface areas and creates a uniform protective layer. An ages old practice to protect iron artefacts is to coat them with animal fat, that is, a mixture of lipids. This “method” is accidentally ingenious: some natural phospholipids found in animal fat have the potential to form a tightly packed self-assembled monolayer on metal oxide surfaces, similar to the surfactant monolayers that have attracted increasing attention lately. Thus, the most primitive corrosion prevention method may point at a way to coat complex iron structures in an industrial environment. Here the ability of phosphatidic acid, a natural lipid, to coat and protect iron surfaces was examined. Iron coated quartz crystal microbalance (QCM) sensors were used for the experiments, to monitor the deposition of the lipid as well as the acidic corrosion (dissolution) of iron in situ, in real time. The sensors were coated by self-assembled monolayers of di-myristoyl phosphatidic acid using the liposome deposition method. In this process, 50-100 nm vesicles formed by the lipid are delivered in an aqueous solution and spontaneously coat the iron surfaces upon contact. QCM and ellipsometry measurements confirmed that continuous bilayer and monolayer surface coatings can be achieved by this method. QCM measurements also confirmed that the layers were corrosion resistant in 0.01M acetic acid solution that would dissolve the thin iron layer in minutes in the absence of the protective coating. XPS results suggested a chemisorption-based mechanism of phosphatidic acid attachment to the iron surface. Hence, liposome deposition of phosphatidic acid offers a suitable solution to coat iron surfaces in inaccessible structures in situ.

N,N'-Dialkylcystine Gemini and Monomeric N-Alkyl Cysteine Surfactants as Corrosion Inhibitors on Mild Steel Corrosion in 1 M HCl Solution: A Comparative Study

Gemini surfactant, N,N'-dialkylcystine 2(C₁₂Cys), derived from cystine, and a monomeric N-alkyl cysteine counterpart, (C₁₂Cys), were synthesized and purified. The characterization of surfactants 2(C₁₂Cys) and (C₁₂Cys) was made by Fourier transform infrared, ¹H NMR, and elemental analysis. The effect of 2(C₁₂Cys) and (C₁₂Cys) on mild steel (MS) corrosion in 1 M HCl solution was explored as a function of their concentration and electrolyte temperature by means of gravimetric and electrochemical experiments (potentiodynamic polarization and Electrochemical impedance spectroscopy), surface analytical techniques (scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDAX) and atomic force microscopy (AFM)) and theoretical study. The investigated compounds exhibited surface active properties and performed as good inhibitors for corrosion control of mild steel (MS) in acid solution. However, compared to monomeric (C₁₂Cys), Gemini surfactant 2(C₁₂Cys) showed high corrosion inhibiting ability at very low concentration. The EIS results revealed a greater charge transfer resistance in 2(C₁₂Cys) solution compared to that in (C₁₂Cys) solution. SEM/EDAX observations validate the development of an inhibitive film by the adsorbed molecules of surfactant on the MS surface. The AFM micrographs supported the SEM/EDAX results and exhibited a lowering in the roughness of the corroded MS surface in the presence of both (C₁₂Cys) and 2(C₁₂Cys) surfactants. Further, quantum chemical calculations and Monte Carlo simulations were used to study the dependence of corrosion inhibiting efficacy on the molecular structure and adsorption strength.

Adsorption and Corrosion Inhibition Behaviour of Zwitterionic Gemini Surfactant for Mild Steel in 0.5 M HCl

The adsorption and corrosion inhibition behaviour of zwitterionic gemini surfactant, 2-decyl phosphate-1-(N,N-dimethyl,N-tetradecylammonium) ethane on mild steel in 0.5 M HCl in the temperature range of 25–65°C has been investigated. The zwitterionic gemini surfactant was synthesized, purified and characterized using nuclear magnetic resonance (NMR) spectroscopy. Surface tension measurements were carried out to evaluate the surface and thermodynamic properties of the surfactant in 0.5 M HCl. Weight loss measurements, potentiodynamic polarization measurements, electrochemical impedance (EIS) measurements and thermodynamic/kinetic parameters were applied to elaborate the adsorption and corrosion inhibition mechanism of the surfactant. Surface morphology of the mild steel specimen corroded in unihibited and inhibited acid was also evaluated using scanning electron microscopy (SEM). The zwitterionic gemini surfactant acts as an excellent inhibitor for mild steel corrosion in 0.5 M HCl; the inhibition efficiency (IE) of inhibitor is concentration and temperature dependent. The evaluated gemini surfactant performed as a mixed-type corrosion inhibitor. The adsorption of surfactant on mild steel surface obeyed Langmuir's adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitor and the mild steel surface.

Theoretical and experimental studies of the corrosion inhibition effect of nitrotetrazolium blue chloride on copper in 0.1 M H2SO4

Theoretical and experimental studies of the corrosion inhibition effect of nitrotetrazolium blue chloride on copper in 0.1 M H₂SO₄.

Cementation of colloidal particles on electrodes in a galvanic microreactor

We have studied the processes leading to the cementation of colloidal particles during their autonomous assembly on corroding copper electrodes within a Cu-Au galvanic microreactor. We determined the onset of particle immobilization through particle tracking, monitored the dissolution of copper as well as the deposition of insoluble products of the corrosion reactions in situ, and showed that particle immobilization initiated after reaction products (RPs) began to deposit on the electrode substrate. We further demonstrated that the time and the extent of RP precipitation and thus the strength of the particle-substrate bond could be tuned by varying the amount of copper in the system and the microreactor pH. The ability to cement colloidal particles at locations undergoing corrosion illustrates that the studied colloidal assembly approach holds potential for applications in dynamic material property adaptation.

Directed motion of colloidal particles in a galvanic microreactor

The mechanisms leading to the deposition of colloidal particles in a copper-gold galvanic microreactor are investigated. Using in situ current density measurements and particle velocimetry, we establish correlations between the spatial arrangement and the geometry of the electrodes, current density distribution, and particle aggregation behavior. Ionic transport phenomena are responsible for the occurrence of strongly localized high current density at the edges and corners of the copper electrodes at large electrode separation, leading to a preferential aggregation of colloidal particles at the electrode edges. Preferential aggregation appears to be the result of a combination of electrophoretic effects and changes in bulk electrolyte flow patterns. We demonstrate that electrolyte flow is most likely driven by electrochemical potential gradients of reaction products formed during the inhomogeneous copper dissolution.

Nanoscale investigation of the impact of pH and orthophosphate on the corrosion of copper surfaces in water

Advanced surface characterization techniques were used to systematically investigate either the corrosion or passivation of copper after immersion in water as impacted by pH and orthophosphate water chemistries. Atomic force microscopy, depth profiling with time-of-flight secondary ion mass spectrometry, and X-ray diffraction were used to evaluate changes in surface chemistry of copper surfaces resulting from various chemical treatments. Nanoscale differences in surface morphology are clearly evident after 6 and 24 h immersion in water samples. Orthophosphate and pH dramatically influence the evolution and progression of changes during surface corrosion. For example, in the absence of orthophosphate the surface of copper exposed to water at pH 6 had formed relatively large cubic crystals on the surface up to 400 nm in height. In the presence of orthophosphate, the morphology and growth rate of corrosion byproduct changed dramatically, and the formation of identifiable crystals diminished. These investigations provide insight into the mechanisms of surface passivation and the evolution of nanoscale mineral deposits on surfaces at very early stages of the corrosion of copper surfaces in water.